The present invention generally relates to catalyst compositions useful for the polymerization or oligomerization of olefins, and to processes using the catalyst compositions. Certain of these catalyst compositions comprise N-pyrrolyl substituted nitrogen donors.
Olefin polymers are used in a wide variety of products, from sheathing for wire and cable to film. Olefin polymers are used, for instance, in injection or compression molding applications, in extruded films or sheeting, as extrusion coatings on paper, for example photographic paper and digital recording paper, and the like. Improvements in catalysts have made it possible to better control polymerization processes and, thus, influence the properties of the bulk material. Increasingly, efforts are being made to tune the physical properties of plastics for lightness, strength, resistance to corrosion, permeability, optical properties, and the like, for particular uses. Chain length, polymer branching and functionality have a significant impact on the physical properties of the polymer. Accordingly, novel catalysts are constantly being sought in attempts to obtain a catalytic process for polymerizing olefins which permits more efficient and better-controlled polymerization of olefins.
Conventional polyolefins are prepared by a variety of polymerization techniques, including homogeneous liquid phase, gas phase, and slurry polymerization. Certain transition metal catalysts, such as those based on titanium compounds (e.g. TiCl3 or TiCl4) in combination with organoaluminium cocatalysts, are used to make linear and linear low-density polyethylenes as well as poly-xcex1-olefins such as polypropylene. These so-called xe2x80x9cZiegler-Nattaxe2x80x9d catalysts are quite sensitive to oxygen and are ineffective for the copolymerization of nonpolar and polar monomers. Following the early discovery of Ziegler-Natta catalysts, there has been intense recent interest in the development and study of homogeneous early transition metal (Group 4-6) catalysts for the polymerization of olefins. These well-defined catalysts, which were first viewed as mechanistic models for heterogeneous Ziegler-Natta catalysts, are receiving increasing commercial attention. Recent advances in Group 4-6 single-site olefin polymerization catalysis include the following.
The following documents describe the use of monocyclopentadienyl amido titanium complexes for the polymerization of olefins as described by J. M. Canich, EP 420,436 (1991) and Stevens et al., EP 416,815 (1991). Waymouth et al., Science, 1995, 267, 217, disclose the use of oscillating catalysts based on unbridged substituted indenyl complexes of zirconium. Mitsui Chemicals Inc. disclose the use of nitrogen/oxygen chelate ligands on Group 4-6 transition metals as catalysts for the polymerization of olefins, EP 874,005 (1998). McConville et al., J. Am. Chem. Soc., 1996, 118, 10008-10009, describe the living polymerization of olefins with chelating diamido complexes of Ti and Zr. Schrock et al., J. Am. Chem. Soc., 1997, 119, 3830, J. Am. Chem. Soc., 1999, 121, 5797, also describe catalysts comprising chelating diamido complexes of Ti and Zr. DSM (WO 94/14854 and EP 0 532 098 A1), BP (EP 0 641 804 A2 and EP 0 816 384 A2), Chevron (WO 94/11410), and Exxon (WO 94/01471) describe the use of Group 4-6 imido catalysts for the polymerization of olefins. Jordan et al., WO 98/40421, disclose the use of novel cationic Group 13 complexes incorporating bidentate ligands as olefin polymerization catalysts.
Recent advances in Group 8-10 catalysts for the polymerization of olefins include the following.
European Patent Application No. 381,495 describes the polymerization of olefins using palladium and nickel catalysts, which contain selected bidentate phosphorous containing ligands.
U. Klabunde, U.S. Pat. Nos. 4,906,754, 4,716,205, 5,030,606, and 5,175,326, describes the conversion of ethylene to polyethylene using anionic phosphorous, oxygen donors ligated to Ni(II). The polymerization reactions were run between 25 and 100xc2x0 C. with modest yields, producing linear polyethylene having a weight-average molecular weight ranging between 8K and 350 K. In addition, Klabunde describes the preparation of copolymers of ethylene and functional group containing monomers.
M. Peuckert et al., Organomet. 1983, 2(5), 594, disclose the oligomerization of ethylene using phosphine/carboxylate donors ligated to Ni(II), which showed modest catalytic activity (0.14 to 1.83 TO/s). The oligomerizations were carried out at 60 to 95xc2x0 C. and 10 to 80 bar ethylene in toluene, to produce xcex1-olefins.
R. E. Murray, U.S. Pat. Nos. 4,689,437 and 4,716,138, describes the oligomerization of ethylene using phosphine, sulfonate donors ligated to Ni(II). These complexes show catalyst activities approximately 15 times greater than those reported with phosphine, carboxylate analogs.
W. Keim et al., Angew. Chem. Int. Ed. Eng., 1981, 20, 116, and V. M. Mohring et al., Angew. Chem. Int. Ed. Eng., 1985, 24, 1001, disclose the polymerization of ethylene and the oligomerization of xcex1-olefins with aminobis(imino)phosphorane nickel catalysts.
Wilke, Angew. Chem. Int. Ed. Engl., 1988, 27, 185, describes a nickel allyl phosphine complex for the polymerization of ethylene.
K. A. O. Starzewski et al., Angew. Chem. Int. Ed. Engl., 1987, 26, 63, and U.S. Pat. No. 4,691,036, describe a series of bis(ylide) nickel complexes, used to polymerize ethylene to provide high molecular weight linear polyethylene.
L. K. Johnson et al., WO 96/23010; U.S. Pat. Nos. 5,866,663; 5,886,224; 5,891,963; 5,880,323; and 5,880,241; disclose the polymerization of olefins using cationic nickel, palladium, iron, and cobalt complexes containing diimine and bisoxazoline ligands. This document also describes the polymerization of ethylene, acyclic olefins, and/or selected cyclic olefins and optionally selected unsaturated acids or esters such as acrylic acid or alkyl acrylates to provide olefin homopolymers or copolymers. L. K. Johnson et al., J. Am. Chem. Soc., 1995, 117, 6414, describe the polymerization of olefins such as ethylene, propylene, and 1-hexene using cationic xcex1-diimine-based nickel and palladium complexes. These catalysts have been described to polymerize ethylene to high molecular weight branched polyethylene. In addition to polymerizing ethylene, the Pd complexes act as catalysts for the polymerization and copolymerization of olefins and methyl acrylate.
WO 97/02298 discloses the polymerization of olefins using a variety of neutral N, O, P, or S donor ligands, in combination with a nickel(0) compound and an acid.
Eastman Chemical Company has recently described in a series of patent applications (WO 98/40374, WO 98/37110, WO 98/47933, and WO 98/40420) several new classes of Group 8-10 transition metal catalysts for the polymerization of olefins. Also described are several new polymer compositions derived from epoxybutene and derivatives thereof.
Brown et al., WO 97/17380, WO 97/48777, WO 97/48739, and WO 97/48740, describe the use of Pd xcex1-diimine catalysts for the polymerization of olefins including ethylene in the presence of air and water.
Fink et al., U.S. Pat. No. 4,724,273, describe the polymerization of xcex1-olefins using aminobis(imino)phosphorane nickel catalysts and the compositions of the resulting poly(xcex1-olefins).
Recently, Vaughan et al., WO 97/48736, Denton et al., WO 97/48742, and Sugimura et al., WO 97/38024, describe the polymerization of ethylene using silica supported xcex1-diimine nickel catalysts.
Phillips, EP 884,331, discloses the use of nickel xcex1-diimine catalysts for the polymerization of ethylene in their slurry loop process.
Neutral nickel catalysts for the polymerization of olefins are described in WO 98/30610; WO 98/30609; WO 98/42665; and WO 98/42664.
Highly active iron and cobalt catalysts ligated by pyridine bis(imines) for the polymerization and oligomerization of ethylene have been independently described by the University of North Carolina-Chapel Hill (WO 99/02472), DuPont (WO 98/27124), BP Chemical and Imperial College (WO 99/12981).
Also recently, Canich et al., WO 97/48735, and Mecking, DE 19707236 A1, describe the use of mixed xcex1-diimine catalysts with Group 4 transition metal catalysts for the polymerization of olefins. Additional recent developments are described by Sugimura et al. in JP 96-84344 and JP 96-84343, by Yorisue et al. in JP 96-70332, by McLain et al. in WO 98/03559, by Weinberg et al. in WO 98/03521, by Wang et al. in WO 99/09078, by Coughlin in WO 99/10391, and by Matsunaga et al. in WO 97/48737.
Notwithstanding these advances in non-Ziegler-Natta catalysis, there remains a need for new transition metal catalysts, particularly those which are more thermally stable, allow for new polymer microstructures, or are more functional group tolerant. In addition, there is a need for novel methods of polymerizing olefins employing such catalysts, and for the novel polymers which result.
A number of transition metal complexes containing nitrogen donor ligands have proven valuable as catalysts for olefin polymerization. A key feature of many of these catalysts is the introduction of steric hindrance through the use of a substituted aryl group on the ligated nitrogen. The steric bulk associated with such fragments tends to suppress premature chain transfer and may, in some cases, stabilize the catalyst towards decomposition, increase the catalyst activity, act to modify the polymer microstructure, or otherwise have beneficial effects.
We have found that catalysts comprising 1-pyrrolyl or substituted 1-pyrrolyl substituted N-donor ligands represent a highly effective and versatile new class of olefin polymerization catalysts. Indeed, we have discovered that the use of such fragments represents a new polyolefin catalyst design principle, wherein aryl substituted nitrogen donors of existing polyolefin catalysts are replaced by 1-pyrrolyl substituted nitrogen donors, as shown in Scheme I, where M is Sc, a Group 4-10 transition metal, Al or Ga, and
R3a-i are each independently H, hydrocarbyl, substituted hydrocarbyl, heteroatom connected hydrocarbyl, heteroatom connected substituted hydrocarbyl, fluoroalkyl, silyl, boryl, fluoro, chloro, bromo, cyano, or nitro, and where any two of R3a-i may be linked by a bridging group. 
This strategy is expected to apply to essentially all previously reported olefin polymerization and oligomerization catalysts incorporating an aryl-substituted nitrogen donor ligand. Thus, catalysts reported in U.S. Pat. Nos. 5,866,663; 5,886,224; 5,891,963; 5,880,323; 5,880,241, and in WO 96/23010, WO 99/10391, WO 99/05189, WO 98/56832, WO 98/03559, WO 98/47934, W097/02298, WO 98/30609, WO 98/42665, WO 98/42664, WO 98/47933, WO 98/40420, WO 98/40374, EP 420,436 (1991), EP 416,815 (1991), Science, 1995, 267, 217, EP 874,005(1998), J. Am. Chem. Soc., 1996, 118, 10008-10009, WO 94/14854, EP 0 532 098 A1, EP 0 641 804 A2, EP 0 816 384 A2, WO 94/11410, WO 94/01471, WO 98/40421, and Chem. Commun., 1998, 313, which have their aryl substituted nitrogen donor fragment or fragments replaced by a N-pyrrol-1-yl or substituted N-pyrrol-1-yl nitrogen donor fragment or fragments are all contemplated to be within the scope of our invention. All U.S. Patents referred to herein are incorporated by reference. Also provided are certain ligands, as depicted in Sets 1-17 below, which are useful as intermediates in the preparation of the polyolefin polymerization and oligomerization catalyst compositions of the present invention.
While catalysts containing N-donors substituted by pyrrol-1-yl or substituted pyrrol-1-yl groups represent a preferred class, N-donor ligands substituted by other types of xe2x80x94NR2aR2b groups, where R2a and R2b are each independently H, hydrocarbyl, substituted hydrocarbyl, silyl, boryl, or ferrocenyl, and where R2a and R2b may be connected to form a ring, are also expected to be useful in constituting olefin polymerization catalysts. Examples of cyclic xe2x80x94NR2aR2b groups are shown in Scheme X, wherein R3a-d are as defined above, and include 2,6-dialkyl-4-oxo-4H-pyridin-1-yl, 2,5-dialkyl- 1-imidazolyl, and 2,6-dimethyl-3-methoxycarbonyl-4-oxo-4H-pyridin-1-yl groups. 
It is expected that those cyclic xe2x80x94NR2aR2b groups wherein the electronic characteristics of the nitrogen of the xe2x80x94NR2aR2b group are similar to those of a 1-pyrrolyl nitrogen will be especially useful. Catalysts containing N-donors substituted by cyclic xe2x80x94PR4aR4b groups (wherein R4a and R4b are each independently hydrocarbyl, substituted hydrocarbyl, heteroatom connected hydrocarbyl, or heteroatom connected substituted hydrocarbyl, and wherein R4a and R4b may be linked by a bridging group), including especially 1-phospholyl or substituted 1-phospholyl groups, are similarly expected to be useful in constituting olefin polymerization catalysts.
Thus, in a first aspect, this invention relates to a catalyst composition for the polymerization or oligomerization of olefins, comprising a metal complex ligated by a monodentate, bidentate, tridentate, or tetradentate ligand, wherein at least one of the donor atoms of the ligand is a nitrogen atom substituted by a 1-pyrrolyl or substituted 1-pyrrolyl group; wherein:
the remaining donor atoms of the ligand are selected from the group consisting of C, N, P, As, O, S, and Se; and wherein
said metal of said metal complex is selected from the group consisting of Sc, Ta, Ti, Zr, Hf, V, Nb, Cr, Mo, W, Mn, Re, Fe, Ru, Os, Co, Rh, Ir, Ni, Cu, Pd, Pt, Al, and Ga.
Preferred catalyst compositions in this first aspect are those comprising a bidentate or tridentate ligand. Numerous examples of such catalyst compositions are contained herein.
In a second aspect, this invention relates to a process for the polymerization or oligomerization of olefins, which comprises contacting one or more olefins with the catalyst composition of the first aspect. Polymerization reaction temperatures of between about 20 and about 160xc2x0 C. are preferred, with temperatures between about 60 and about 100xc2x0 C. being especially preferred. Ethylene, propylene, 1-butene, 1-hexene and 1-octene are preferred olefin monomers. When ethylene is used as the primary or predominant olefin monomer, pressures between about 1 and about 100 atm are preferred.
In a third aspect, this invention relates to a catalyst composition for the polymerization or oligomerization of olefins, comprising a catalyst composition of the first aspect, wherein the metal is selected from the group consisting of Co, Fe, Ni, and Pd, and the ligand is a neutral bidentate ligand.
A first preferred embodiment of this third aspect are those catalyst compositions wherein the metal complex is either (i) a compound of formula XIa, or (ii) the reaction product of Ni(1,5-cyclooctadiene)2, B(C6F5)3, one or more olefins, and said neutral bidentate ligand: 
wherein:
M is Fe, Co, Ni or Pd;
D1, D2, and G collectively comprise the neutral bidentate ligand;
D1 and D2 are monodentate donors linked by a bridging group G, wherein at least one of D1 and D2 is ligated to the metal M by a nitrogen atom substituted by a 1-pyrrolyl or a substituted 1-pyrrolyl group;
T is H, hydrocarbyl, substituted hydrocarbyl, or other group capable of inserting an olefin;
L is an olefin or a neutral donor group capable of being displaced by an olefin; in addition, T and L may be taken together to form a xcfx80-allyl or xcfx80-benzyl group; and
Xxe2x88x92 is a weakly coordinating anion.
A second preferred embodiment in this third aspect are those catalyst compositions wherein the metal complex is the reaction product of a compound of formula XIb and a second compound Y2. 
wherein:
M is Fe, Co, Ni or Pd;
D1, D2, and G collectively comprise the neutral bidentate ligand;
D1 and D2 are monodentate donors linked by a bridging group G, wherein at least one of D1 and D2 is ligated to the metal M by a nitrogen atom substituted by a 1-pyrrolyl or a substituted 1-pyrrolyl group;
Q and W1 are each independently fluoro, chloro, bromo or iodo, hydrocarbyl, substituted hydrocarbyl, heteroatom connected hydrocarbyl, heteroatom connected substituted hydrocarbyl, or collectively sulfate, or may be taken together to form a xcfx80-allyl, xcfx80-benzyl, or acetylacetonate group, in which case a weakly coordinating counteranion Xxe2x88x92 is also present; and
Y2 is a neutral Lewis acid capable of abstracting Qxe2x88x92 or W1xe2x88x92 to form a weakly coordinating anion, a cationic Lewis acid whose counterion is a weakly coordinating anion, or a Bronsted acid whose conjugate base is a weakly coordinating anion.
A third, more preferred, embodiment in this third aspect are those catalyst compositions of the first or second embodiments in which the metal M in formulas XIa or XIb is Ni and the neutral bidentate ligand is selected from Set 1: 
wherein:
R2x,y are each independently H, hydrocarbyl, substituted hydrocarbyl, heteroatom connected hydrocarbyl, heteroatom connected substituted hydrocarbyl; silyl, boryl, or ferrocenyl; in addition, R2x and R2y may be linked by a bridging group; and
R3a-h are each independently H, hydrocarbyl, substituted hydrocarbyl, heteroatom connected hydrocarbyl, heteroatom connected substituted hydrocarbyl, fluoroalkyl, silyl, boryl, fluoro, chloro, bromo, cyano, or nitro; in addition, any two of R3a-h may be linked by a bridging group.
In a fourth preferred embodiment, the catalyst compositions of the third aspect are attached to a solid support, with those catalyst compositions wherein the metal is nickel and the solid support is silica representing an especially preferred, fifth embodiment.
In a fourth aspect, this invention relates to a process for the polymerization or oligomerization of olefins, which comprises contacting one or more olefins with the catalyst composition of the third aspect.
A first preferred embodiment of this fourth aspect is the process wherein linear xcex1-olefins are obtained.
A second preferred embodiment of this fourth aspect is the process wherein a polyolefin wax is obtained.
In a fifth aspect, this invention relates to a process for the polymerization of olefins, which comprises contacting one or more olefins with a catalyst composition of the fourth or fifth embodiment of the third aspect. A first preferred embodiment of this fifth aspect is the process wherein the metal is Ni, the solid support is silica, and the catalyst is activated by treatment with an alkylaluminum in a gas phase, fluidized bed, olefin polymerization reactor, or in an inlet stream thereof. A second, more preferred, embodiment of this fifth aspect is the process wherein the alkylaluminum is trimethylaluminum.
The in situ catalyst activation protocol described as a first preferred embobiment of the fifth aspect represents a significant process breakthrough. The in situ catalyst activation allows for the addition to a gas phase reactor of an inactive or passivated catalyst that is activated in the reactor, and catalyst activity increases as additional sites become activated. This process allows for more convenient catalyst handling as well as improved control and stability of the gas phase process.
In a sixth aspect, this invention relates to a compound selected from Set 2. 
wherein:
R2x,y are each independently H, hydrocarbyl, substituted hydrocarbyl, heteroatom connected hydrocarbyl, heteroatom connected substituted hydrocarbyl; silyl, boryl, or ferrocenyl; in addition, R2x and R2y may be linked by a bridging group;
R3a-h are each independently H, hydrocarbyl, substituted hydrocarbyl, heteroatom connected hydrocarbyl, heteroatom connected substituted hydrocarbyl, fluoroalkyl, silyl, boryl, fluoro, chloro, bromo, cyano, or nitro; in addition, any two of R3a-h may be linked by a bridging group.
In a seventh aspect, this invention relates to a catalyst composition for the polymerization or oligomerization of olefins, comprising either (i) a cationic Group 8-10 transition metal complex of a neutral bidentate ligand selected from Set 3, or a tautomer thereof, and a weakly coordinating anion Xxe2x88x92, or (ii) the reaction product of Ni(1,5-cyclooctadiene)2, B(C6F5)3, one or more olefin monomers, and a neutral bidentate ligand selected from Set 3: 
wherein:
R2a-f,x-z are each independently H, hydrocarbyl, substituted hydrocarbyl, heteroatom connected hydrocarbyl, or heteroatom connected substituted hydrocarbyl; R2a-f may also be silyl, boryl, or ferrocenyl; in addition, any two of R2a-d, or R2x and R2y, may be linked by a bridging group;
R3a-j are each independently H, hydrocarbyl, substituted hydrocarbyl, heteroatom connected hydrocarbyl, heteroatom connected substituted hydrocarbyl, fluoroalkyl, silyl, boryl, fluoro, chloro, bromo, cyano, or nitro; in addition, any two of R3a-j may be linked by a bridging group;
R4a and R4b are each independently hydrocarbyl, substituted hydrocarbyl, heteroatom connected hydrocarbyl, or heteroatom connected substituted hydrocarbyl; in addition, R4a and R4b may be linked by a bridging group;
G1 is hydrocarbyl, substituted hydrocarbyl, heteroatom connected hydrocarbyl, or heteroatom connected substituted hydrocarbyl;
G1, C, and N collectively comprise a 5- or 6-membered heterocyclic ring;
G2 is hydrocarbyl, substituted hydrocarbyl, heteroatom connected hydrocarbyl, or hetero atom connected substituted hydrocarbyl;
G2, V1, N, and N collectively comprise a 5- or 6-membered heterocyclic ring;
V1 is CR3j, N, or PR4aR4b;
E1 is O, S, Se, or NR2e;
E2 and E3 are O, S, or NR2e; and
Q1 is Cxe2x80x94R3j, PR4aR4b, S(E2)(NR2eR2f), or S(E2)(E3R2e);
provided that the ligand is not of the formula a15, which has been previously described in the third embodiment of the third aspect of the present invention.
In an eighth aspect, this invention relates to a process for the polymerization or oligomerization of olefins, which comprises contacting one or more olefins with the catalyst composition of the seventh aspect. Polymerization reaction temperatures between about 20 and about 160xc2x0 C. are preferred, with temperatures between about 60 and about 100xc2x0 C. being more preferred. Ethylene, propylene, 1-butene, 1-hexene and 1-octene are preferred olefin monomers. When ethylene is used as the primary or predominant olefin monomer, pressures between about 1 and about 100 atm are preferred.
In a ninth aspect, this invention relates to a ligand selected from Set 4: 
wherein:
R2a-f,x-z are each independently H, hydrocarbyl, substituted hydrocarbyl, heteroatom connected hydrocarbyl, or heteroatom connected substituted hydrocarbyl; R2a-f may also be silyl, boryl, or ferrocenyl; in addition, any two of R2a-d, or R2x and R2y, may be linked by a bridging group;
R3a-j are each independently H, hydrocarbyl, substituted hydrocarbyl, heteroatom connected hydrocarbyl, heteroatom connected substituted hydrocarbyl, fluoroalkyl, silyl, boryl, fluoro, chloro, bromo, cyano, or nitro; in addition, any two of R3a-j may be linked by a bridging group;
R4a and R4b are each independently hydrocarbyl, substituted hydrocarbyl, heteroatom connected hydrocarbyl, or heteroatom connected substituted hydrocarbyl; in addition, R4a and R4b may be linked by a bridging group;
G1 is hydrocarbyl, substituted hydrocarbyl, heteroatom connected hydrocarbyl, or heteroatom connected substituted hydrocarbyl;
G1, C, and N collectively comprise a 5- or 6-membered heterocyclic ring;
G2 is hydrocarbyl, substituted hydrocarbyl, heteroatom connected hydrocarbyl, or heteroatom connected substituted hydrocarbyl;
G2, V1, N, and N collectively comprise a 5- or 6-membered heterocyclic ring;
V1 is CR3j, N, or PR4aR4b;
E1 is O, S, Se, or NR2e;
E2 and E3 are O, S, or NR2e; and
Q1 is Cxe2x80x94R3j, PR4aR4b, S(E2)(NR2eR2f), or S(E2)(E3R2e);
provided that (i) the ligand is not of the formula al5, which has been previously described in the sixth aspect, (ii) when the ligand is of the formula b7, and E3 is O, R3a-d are H, and R2x is H, the pyrrol-1-yl group is other than carbazol-9-yl, 3-phenylinden-1-yl or unsubstituted pyrrol-1-yl, and (iii) when the ligand is of formula a55, it is other than carbazol-9-yl-quinolin-2-ylmethylene-amine.
In a tenth aspect, this invention relates to a catalyst composition for the polymerization or oligomerization of olefins, comprising a catalyst composition of the first aspect, wherein the metal is selected from the group consisting of Co, Ni, and Pd, and the ligand is a monoanionic bidentate ligand. Preferred catalyst compositions in this tenth aspect are those wherein the metal is nickel; more preferred are those catalyst compositions wherein the metal complex is of formula XII: 
wherein:
M is nickel;
D1, D2, and G collectively comprise the monoanionic bidentate ligand;
D1 and D2 are monodentate donors linked by a bridging group G, wherein at least one of D1 and D2 is ligated to the metal M by a nitrogen atom substituted by a 1-pyrrolyl or a substituted 1-pyrrolyl group;
T is H, hydrocarbyl, substituted hydrocarbyl, or other group capable of inserting an olefin; and
L is an olefin or a neutral donor group capable of being displaced by an olefin; in addition, T and L may be taken together to form a xcfx80-allyl or xcfx80-benzyl group.
Even more preferred catalyst compositions in this tenth aspect are those wherein the monoanionic bidentate ligand is selected from Set 5, or a tautomer thereof: 
wherein:
R2x-z are each independently H, hydrocarbyl, substituted hydrocarbyl, heteroatom connected hydrocarbyl, or heteroatom connected substituted hydrocarbyl;
R3a-j are each independently H, hydrocarbyl, substituted hydrocarbyl, heteroatom connected hydrocarbyl, heteroatom connected substituted hydrocarbyl, fluoroalkyl, silyl, boryl, fluoro, chloro, bromo, cyano, or nitro; in addition, any two of R3a-j may be linked by a bridging group;
R4a and R4b are each independently hydrocarbyl, substituted hydrocarbyl, heteroatom connected hydrocarbyl, or heteroatom connected substituted hydrocarbyl; in addition, R4a and R4b may be linked by a bridging group;
E2 and E3 are O, S, or NR2x; and
Q is Cxe2x80x94R3j, PR4aR4b, S(E2)(NR2yR2z), or S(E2)(E3R2x).
Also preferred in this tenth aspect are those catalyst compositions wherein the metal complex is attached to a solid support, with silica being an especially preferred support.
In an eleventh aspect, this invention relates to a process for the polymerization or oligomerization of olefins, which comprises contacting one or more olefins with the catalyst composition of the tenth aspect. Polymerization reaction temperatures between about 20 and about 160xc2x0 C. are preferred, with temperatures between about 60 and about 100xc2x0 C. being more preferred. Ethylene, propylene, 1-butene, 1-hexene, 1-octene, norbornene and substituted norbornenes are preferred olefin monomers. When ethylene is used as the primary or predominant olefin monomer, pressures between about 1 and about 100 atm are preferred.
In a twelfth aspect, this invention relates to a catalyst composition for the polymerization or oligomerization of olefins, comprising a catalyst composition of the first aspect, wherein the metal is selected from the group consisting of Mn, Fe, Ru, and Co, and the ligand is a neutral tridentate ligand. Preferred catalyst compositions in this twelfth aspect are those wherein the metals are Fe and Co; more preferred are those catalyst compositions comprising a compound of formula XIII: 
wherein:
M is Co or Fe;
D1-3 are monodentate donors which are linked by a bridging group(s) to collectively comprise the neutral tridentate ligand, wherein at least one of D1, D2, and D3 is ligated to the metal M by a nitrogen atom substituted by a 1-pyrrolyl or a substituted 1-pyrrolyl group;
T is H, hydrocarbyl, substituted hydrocarbyl or other group capable of inserting an olefin;
L is an olefin or a neutral donor group capable of being displaced by an olefin; in addition, T and L may be taken together to form a xcfx80-allyl or xcfx80-benzyl group; and
Xxe2x88x92 is a weakly coordinating anion.
Even more preferred catalyst compositions in this twelfth aspect are those wherein the neutral tridentate ligand is selected from Set 6, or a tautomer thereof: 
wherein:
R2c,x-z are each independently H, hydrocarbyl, substituted hydrocarbyl, heteroatom connected hydrocarbyl, or heteroatom connected substituted hydrocarbyl; in addition, R2x and R2y may be linked by a bridging group in the ligand of formula h6;
R3a-m are each independently H, hydrocarbyl, substituted hydrocarbyl, heteroatom connected hydrocarbyl, heteroatom connected substituted hydrocarbyl, fluoroalkyl, silyl, boryl, fluoro, chloro, bromo, cyano, or nitro; in addition, any two of R3a-m may be linked by a bridging group;
R4a-d are each independently hydrocarbyl, substituted hydrocarbyl, heteroatom connected hydrocarbyl, or heteroatom connected substituted hydrocarbyl; in addition, any two of R4a-z may be linked by a bridging group or groups;
G3 is hydrocarbyl or substituted hydrocarbyl;
E2 and E3 are O, S, or Se; and
E4 is O, S, or Se.
Also preferred in this twelfth aspect are those catalyst compositions wherein the metal complex is attached to a solid support, with silica being an especially preferred support.
In a thirteenth aspect, this invention also relates to a process for the polymerization or oligomerization of olefins, which comprises contacting one or more olefins with a catalyst composition of the twelfth aspect. Polymerization reaction temperatures between about 20 and about 160xc2x0 C. are preferred, with temperatures between about 60 and about 100xc2x0 C. being more preferred. Ethylene, propylene, 1-butene, 1-hexene and 1-octene are preferred olefin monomers. When ethylene is used, pressures between about 1 and about 100 atm are preferred. Also preferred are those embodiments wherein non-supported catalysts are used to produce linear xcex1-olefins or polyolefin waxes.
In a fourteenth aspect, this invention relates to a catalyst composition for the polymerization of olefins, comprising a Ti, Zr, or Hf complex of a dianionic bidentate ligand, wherein at least one of the donor atoms of the ligand is a nitrogen atom substituted by a 1-pyrrolyl or substituted 1-pyrrolyl group; wherein the remaining donor atoms of the ligand are selected from the group consisting of C, N, P, As, 0, S, and Se. Preferred catalyst compositions in this fourteenth aspect are those wherein the metal complex is a compound of formula XIV: 
wherein:
M is Zr or Ti;
D1, D2, and G collectively comprise the dianionic bidentate ligand;
D1 and D2 are monodentate donors linked by a bridging group G, wherein at least one of D1 and D2 is ligated to the metal M by a nitrogen atom substituted by a
1-pyrrolyl or a substituted 1-pyrrolyl group;
T is H, hydrocarbyl, substituted hydrocarbyl, or other group capable of inserting an olefin; and
Xxe2x88x92 is a weakly coordinating anion.
More preferred catalyst compositions in this fourteenth aspect are those wherein the dianionic bidentate ligand is selected from Set 7, or a tautomer thereof: 
wherein:
R3a-h are each independently H, hydrocarbyl, substituted hydrocarbyl, heteroatom connected hydrocarbyl, heteroatom connected substituted hydrocarbyl, fluoroalkyl, silyl, boryl, fluoro, chloro, bromo, cyano, or nitro; in addition, any two of R3a-h may be linked by a bridging group; and
G4 is a divalent bridging hydrocarbyl, substituted hydrocarbyl, heteroatom connected hydrocarbyl, or heteroatom connected substituted hydrocarbyl.
Also preferred in this fourteenth aspect are those catalyst compositions which are attached to a solid support.
In a fifteenth aspect, this invention relates to a process for the polymerization of olefins, comprising contacting one or more olefins with the catalyst composition of the fourteenth aspect, and optionally an aluminum or boron-centered Lewis acid. Examples of aluminum or boron-centered Lewis acids include MAO, B(C6F5)3, triisobutylaluminum modified MAO, and B(C12F9)3. Polymerization reaction temperatures between about 20 and about 1 60xc2x0 C. are preferred, with temperatures between about 60 and about 100xc2x0 C. being more preferred. Ethylene, proplene, 1-butene, 1-hexene and 1-octene are preferred olefin monomers. When ethylene is used, pressures between about 1 and about 100 atm are preferred.
In a sixteenth aspect, this invention relates to a catalyst composition for the polymerization of olefins, comprising a Ti, Zr, or Hf complex of a monoanionic bidentate ligand, wherein at least one of the donor atoms of the ligand is a nitrogen atom substituted by a 1-pyrrolyl or substituted 1-pyrrolyl group; wherein the remaining donor atoms of the ligand are selected from the group consisting of C, N, P, As, O, S, and Se.
Preferred catalyst compositions in the sixteenth aspect are those which optionally further comprise a second compound Y2, wherein the metal complex is a compound of formula XV: 
wherein:
M is Ti, Zr, or Hf;
m and n are integers, defined as follows: when M is Ti and m is 1, n is 2 or 3; when M is Ti and m is 2, n is 1 or 2; when M is Zr and m is 1, n is 3; when M is Zr and m is 2, n is 2; when M is Hf, m is 2 and n is 2;
R3a-i are each independently H, hydrocarbyl, substituted hydrocarbyl, heteroatom connected hydrocarbyl, heteroatom connected substituted hydrocarbyl, silyl, boryl, fluoro, chloro, bromo, or nitro, with the proviso that R3e is other than halogen or nitro; in addition, any two of R3a-i on the same or different N-pyrrol-1-yliminophenoxide ligand may be linked by a bridging group;
Z is H, halogen, hydrocarbyl, substituted hydrocarbyl, heteroatom connected hydrocarbyl, heteroatom connected substituted hydrocarbyl, silyl, allyl, benzyl, alkoxy, carboxylate, amido, nitro, or trifluoromethane sulfonyl; each Z may be the same or different and plural Z may be taken together to form sulfate, oxalate, or another divalent group;
Y2 is selected from the group consisting of a neutral Lewis acid capable of abstracting Zxe2x88x92 to form a weakly coordinating anion, a cationic Lewis acid whose counterion is a weakly coordinating anion, and a Bronsted acid whose conjugate base is a weakly coordinating anion; and
when n is 2 or 3, the metal complex may be a salt, comprising a Ti, Zr, or Hf centered cation with one of the groups Zxe2x88x92 being a weakly coordinating anion.
Even more preferred catalyst compositions in this sixteenth aspect are those wherein the monoanionic bidentate ligand is selected from Set 8, or a tautomer thereof: 
wherein:
R2x is H, hydrocarbyl, substituted hydrocarbyl, heteroatom connected hydrocarbyl, or heteroatom connected substituted hydrocarbyl; and
R3a-d,f-i are each independently H, hydrocarbyl, substituted hydrocarbyl, heteroatom connected hydrocarbyl, heteroatom connected substituted hydrocarbyl, fluoroalkyl, silyl, boryl, fluoro, chloro, bromo, cyano, or nitro; in addition, any two of R3a-d,f-i may be linked by a bridging group.
Also preferred catalyst compositions in this sixteenth aspect are those catalyst compositions which are attached to a solid support, with silica being an especially preferred solid support.
In a seventeenth aspect, this invention also relates to a process for the polymerization of olefins, which comprises contacting one or more olefins with the catalyst composition of the sixteenth aspect, and optionally a second compound Y2; wherein Y2 is selected from the group consisting of (i) a neutral Lewis acid which is capable of reacting with said Ti, Zr, or Hf complex to form a salt comprising a weakly coordinating anion, (ii) a cationic Lewis acid whose counterion is a weakly coordinating anion, and (iii) a Bronsted acid whose conjugate base is a weakly coordinating anion. Polymerization reaction temperatures between about 20 and about 160xc2x0 C. are preferred, with temperatures between about 60 and about 100xc2x0 C. being more preferred. Ethylene, propylene, 1-butene, 1-hexene and 1-octene are preferred olefin monomers. When ethylene is used, pressures between about 1 and about 100 atm are preferred.
In an eighteenth aspect, this invention relates to a catalyst composition for the polymerization of olefins, comprising a Cr, Mo, or W complex of a monodentate dianionic ligand, wherein at least one of the donor atoms of the ligand is a nitrogen atom substituted by a 1-pyrrolyl or substituted 1-pyrrolyl group; wherein the remaining donor atoms of the ligand are selected from the group consisting of C, N, P, As, O, S, and Se. Preferred catalyst compositions in this eighteenth aspect are those which optionally further comprise a second compound Y2, wherein the metal complex is a compound of formula XVI: 
wherein:
M is Cr, Mo, or W;
D1 and D2 are monodentate dianionic ligands that may be linked by a bridging group to collectively comprise a bidentate tetraanionic ligand;
Z1a and Z1b are each, independently H, halogen, hydrocarbyl, substituted hydrocarbyl, heteroatom connected hydrocarbyl, heteroatom connected substituted hydrocarbyl, silyl, allyl, benzyl, alkoxy, carboxylate, amido, nitro, trifluoromethanesulfonyl, or may be taken together to form sulfate, oxalate, or another divalent group;
Y2 is selected from the group consisting of a neutral Lewis acid capable of abstracting (Z1a)xe2x88x92 or (Z1b)xe2x88x92 to form a weakly coordinating anion, a cationic Lewis acid whose counterion is a weakly coordinating anion, and a Bronsted acid whose conjugate base is a weakly coordinating anion; and wherein
the metal complex may be a salt, comprising a Cr, Mo, or W centered cation with one of (Z1a)xe2x88x92 or (Z1b)xe2x88x92 being a weakly coordinating anion.
Even more preferred catalyst compositions in this eighteenth aspect are those wherein the metal is Cr and the monodentate dianionic ligand is selected from Set 9, or a tautomer thereof: 
wherein:
R3a-d are each independently H, hydrocarbyl, substituted hydrocarbyl, heteroatom connected hydrocarbyl, heteroatom connected substituted hydrocarbyl, fluoroalkyl, silyl, boryl, fluoro, chloro, bromo, cyano, or nitro; in addition, any two of R3a-d may be linked by a bridging group.
Also preferred in this eighteenth aspect are those catalyst compositions which are attached to a solid support, with silica being an especially preferred solid support.
In a nineteenth aspect, this invention also relates to a process for the polymerization of olefins, which comprises contacting one or more olefins with the catalyst composition of the eighteenth aspect, and optionally a second compound Y2; wherein Y2 is selected from the group consisting of (i) a neutral Lewis acid which is capable of reacting with said Cr, Mo, or W complex to form a salt comprising a weakly coordinating anion, (ii) a cationic Lewis acid whose counterion is a weakly coordinating anion, and (iii) a Bronsted acid whose conjugate base is a weakly coordinating anion. Polymerization reaction temperatures between about 20 and about 160xc2x0 C. are preferred, with temperatures between about 60 and about 100xc2x0 C. being more preferred. Ethylene, propylene, 1-butene, 1-hexene and 1-octene are preferred olefin monomers. When ethylene is used, pressures between about 1 and about 100 atm are preferred.
In a twentieth aspect, this invention relates to a catalyst composition for the polymerization of olefins, comprising a V, Nb, or Ta complex of a monodentate dianionic ligand, wherein at least one of the donor atoms of the ligand is a nitrogen atom substituted by a 1-pyrrolyl or substituted 1-pyrrolyl group; wherein the remaining donor atoms of the ligand are selected from the group consisting of C, N, P, As, O, S, and Se.
Preferred catalyst compositions in this twentieth aspect are those which optionally further comprise a second compound Y2, wherein the metal complex is a compound of formula XVII: 
wherein:
M is V, Nb, or Ta;
R3a-d are each independently H, hydrocarbyl, substituted hydrocarbyl, heteroatom connected hydrocarbyl, heteroatom connected substituted hydrocarbyl, silyl, boryl, fluoro, chloro, bromo, or nitro; in addition, any two of R3a-d may be linked by a bridging group;
T1b is hydrocarbyl,.substituted hydrocarbyl, heteroatom connected hydrocarbyl, heteroatom connected substituted hydrocarbyl, cyclopentadienyl, substituted cyclopentadienyl, N(hydrocarbyl)2, O(hydrocarbyl), or halide;
Z1a and Z1b are each, independently H, halogen, hydrocarbyl, substituted hydrocarbyl, heteroatom connected hydrocarbyl, heteroatom connected substituted hydrocarbyl, silyl, allyl, benzyl, alkoxy, carboxylate, amido, nitro, trifluoromethane sulfonyl, or may be taken together to form sulfate, oxalate, or another divalent group;
Y2 is selected from the group consisting of a neutral Lewis acid capable of abstracting (Z1a)xe2x88x92 or (Z1b)xe2x88x92 to form a weakly coordinating anion, a cationic Lewis acid whose counterion is a weakly coordinating anion, and a Bronsted acid whose conjugate base is a weakly coordinating anion; and wherein
the metal complex may be a salt, comprising a V, Nb, or Ta centered cation with one of (Z1a)xe2x88x92 or (Z1b)xe2x88x92 being a weakly coordinating anion.
More preferred catalyst compositions in this twentieth aspect are those wherein the monodentate dianionic ligand is selected from Set 10, or a tautomer thereof, and T1b is a N(hydrocarbyl)2 group: 
wherein:
R3a-d are each independently H, hydrocarbyl, substituted hydrocarbyl, heteroatom connected hydrocarbyl, heteroatom connected substituted hydrocarbyl, fluoroalkyl, silyl, boryl, fluoro, chloro, bromo, cyano, or nitro; in addition, any two of R3a-d may be linked by a bridging group.
Even more preferred catalyst compositions in this twentieth aspect are those wherein the metal is V and the metal complex is attached to a solid support.
In a twenty-first aspect, this invention also relates to a process for the polymerization of olefins, which comprises contacting one or more olefins with the catalyst composition of the twentieth aspect, and optionally a second compound Y2; wherein Y2 is selected from the group consisting of (i) a neutral Lewis acid which is capable of reacting with said V, Nb, or Ta complex to form a salt comprising a weakly coordinating anion, (ii) a cationic Lewis acid whose counterion is a weakly coordinating anion, and (iii) a Bronsted acid whose conjugate base is a weakly coordinating anion.
In a twenty-second aspect, this invention relates to a catalyst composition for the polymerization olefins, comprising (i) a cationic Ti, Zr or Hf complex of a mono- or dianionic, nitrogen donor ligand, wherein said nitrogen donor is substituted by a 1-pyrrolyl or substituted 1-pyrrolyl group and is linked by a bridging group to a cyclopentadienyl, phosphacyclopentadienyl, pentadienyl, 6-oxacyclohexadienyl, or borataaryl group which is also ligated to said metal, and optionally, (ii) an aluminum or boron-centered Lewis acid. Preferred catalyst compositions within this twenty-second aspect are those wherein the mono- or dianionic, nitrogen donor ligand is selected from Set 11, or a tautomer thereof: 
wherein:
R2a is H, hydrocarbyl, substituted hydrocarbyl, heteroatom connected hydrocarbyl, heteroatom connected substituted hydrocarbyl, silyl, boryl, or ferrocenyl;
R3a-h are each independently H, hydrocarbyl, substituted hydrocarbyl, heteroatom connected hydrocarbyl, heteroatom connected substituted hydrocarbyl, fluoroalkyl, silyl, boryl, fluoro, chloro, bromo, cyano, or nitro; in addition, any two of R3a-h may be linked by a bridging group;
R4a is hydrocarbyl, substituted hydrocarbyl, heteroatom connected hydrocarbyl, or heteroatom connected substituted hydrocarbyl; and
G is a divalent bridging hydrocarbyl, substituted hydrocarbyl, silyl, heteroatom connected hydrocarbyl, or heteroatom connected substituted hydrocarbyl.
Also preferred catalyst compositions in this twenty-second aspect are those wherein the metal complex is attached to a solid support.
In a twenty-third aspect, this invention also relates to a process for the polymerization of olefins, which comprises contacting one or more olefins with the catalyst composition of the twenty-second aspect. Polymerization reaction temperatures between about 20 and about 160xc2x0 C. are preferred, with temperatures between about 60 and about 100xc2x0 C. being more preferred. Ethylene, propylene, 1-butene, 1-hexene and 1-octene are preferred olefin monomers. When ethylene is used, pressures between about 1 and about 100 atm are preferred.
Notwithstanding the above-noted advances in polyolefin catalysis, set forth in the Background of the Invention section, there remains a need for new catalysts which can not only produce novel polyolefin microstructures or incorporate functional co-monomers, but also possess sufficient thermal stability to be used in existing production reactors, and exhibit an appropriate response to hydrogen under such conditions, so as to allow for control of molecular weight without an unacceptable loss of catalyst productivity. This is particularly true in the case of nickel catalysts comprising bidentate N,N-donor ligands, which typically exhibit very short lifetimes (txc2xd ca. 2-4 min) at 60xc2x0 C., and are generally so severely inhibited by hydrogen that when enough hydrogen is added to bring the molecular weight down to that of a typical commercial linear low density polyethylene (LLDPE), the catalyst productivities at elevated temperature are so low as to be impractical. A common structural feature of these catalysts is that they contain a nitrogen donor substituted by an aromatic or heteroaromatic ring, wherein the substituents ortho to the point of attachment to the ligated nitrogen are alkyl groups, as exemplified by complex XXI.
We have discovered that both the thermal stability and the catalyst productivity in the presence of hydrogen are dramatically improved if the ortho substituents are aryl groups, as exemplified by complex XXII. Productivity improvements of about an order of magnitude, or more, are observed when the ortho-alkyl groups are replaced by ortho-aryl groups. 
Whereas the half-life for catalyst deactivation for complex XXI is about 2-4 minutes at 60xc2x0 C., 200 psig ethylene, the half-life for catalyst deactivation for complex XXII is at least about 32 minutes at 200 psig ethylene, and even at 1 atm ethylene, detectable activity is still observed after 16 hours at 60xc2x0 C.
Without wishing to be bound by theory, the inventors attribute the improved stability to the reversible formation of agostic aryl intermediates in the catalytic chemistry (c.f. structure XXIII, wherein Rp represents the growing polymer chain, Xxe2x88x92 is a weakly coordinating anion, and no specific bonding mode is implied for the interaction of the agostic phenyl group with the nickel center). 
As such, the catalysis no longer involves a strictly bidentate ligand, but rather a variable denticity ligand, whereby the ability of the ligand to donate additional electron density (and possibly also accept xcfx80-electron density from the nickel) is believed to stabilize low coordinate intermediates (e.g. three-coordinate cationic nickel hydride species), which otherwise would rapidly decompose to catalytically inactive species. When ortho-alkyl groups are present, it is believed that rapid cyclometallation occurs to give species which are either permanently deactivated, or which are so slowly reactivated as to render them much less attractive for commercial polyolefin production. Deactivation reactions of this general type have been discussed by Brookhart et al. (J. Am. Chem. Soc., 117, 6414, 1995).
Ligands wherein some, but not all, of the ortho positions are substituted by bromo groups also give rise to catalysts which exhibit enhanced thermal stability and stability towards hydrogen. In contrast, when even one of four ortho substituents in a catalyst of this invention is alkyl, and the rest are aryl, poor thermal stabilities are observed (u2, R7a-c=Ph; R7d=Me or cyclopropyl; R2x,y=Me). Similarly, when all four of the ortho positions are bromo (u4, R7a-d=Br; R2x,y collectively OCH2CH2O), poor thermal stability is also observed. Without wishing to be bound by theory, the inventors believe that catalysts wherein the ortho positions are substituted by groups other than alkyl will exhibit enhanced thermal stability and stability towards hydrogen, provided that at least one of the ortho positions of one of said aromatic or heteroaromatic rings is an aryl or heteroaryl group.
Therefore, although the pro-catalyst may comprise, for example, a bidentate N,Nxe2x80x94N,Oxe2x80x94 or N,P-donor ligand, it is a novel feature of these ortho-aryl substituted ligands that they can reversibly form an additional bonding interaction, thereby helping to stabilize catalytic intermediates under polymerization conditions.
Thus, in a twenty-fourth aspect, this invention relates to a process for the polymerization or oligomerization of olefins, comprising contacting one or more olefins with a catalyst composition comprising a Group 8-10 transition metal complex, wherein said catalyst composition exhibits improved thermal stability, and wherein said metal complex comprises a bidentate or variable denticity ligand comprising one or two nitrogen donor atom or atoms independently substituted by an aromatic or heteroaromatic ring, wherein the ortho positions of said ring(s) are substituted by groups other than H or alkyl; provided that at least one of the ortho positions of at least one of said aromatic or heteroaromatic rings is substituted by an aryl or heteroaryl group.
As used herein, examples of groups other than H or alkyl include aryl, heteroaryl, bromo, fluoroalkyl and cyano.
In a twenty-fifth aspect, this invention also relates to a process for the polymerization or oligomerization of olefins, comprising contacting one or more olefins with a catalyst composition comprising a Group 8-10 transition metal complex, wherein said catalyst composition exhibits improved stability in the presence of an amount of hydrogen effective to achieve chain transfer, and wherein said metal complex comprises a bidentate or variable denticity ligand comprising one or two nitrogen donor atom or atoms independently substituted by an aromatic or heteroaromatic ring, wherein the ortho positions of said ring(s) are substituted by groups other than H or alkyl; provided that at least one of the ortho positions of at least one of said aromatic or heteroaromatic rings is substituted by an aryl or heteroaryl group.
In a twenty-sixth aspect, this invention also relates to a process for the polymerization or oligomerization of olefins, comprising contacting one or more olefins with a catalyst composition comprising a Group 8-10 transition metal complex, wherein said catalyst composition exhibits either improved thermal stability, or exhibits improved stability in the presence of an amount of hydrogen effective to achieve chain transfer, or both, wherein said metal complex comprises a bidentate or variable denticity ligand comprising one or two nitrogen donor atom or atoms independently substituted by an aromatic or heteroaromatic ring, wherein at least one of the ortho positions of at least one of said aromatic or heteroaromatic rings is substituted by an aryl or heteroaryl group which is capable of reversibly forming an agostic bond to said Group 8-10 transition metal under olefin polymerization reaction conditions.
In a twenty-seventh aspect, this invention also relates to a process for the polymerization or oligomerization of olefins, comprising contacting one or more olefins with a catalyst composition comprising a Group 8-10 transition metal complex, wherein said catalyst composition exhibits either improved thermal stability, or exhibits improved stability in the presence of an amount of hydrogen effective to achieve chain transfer, or both, wherein said composition comprises a bidentate or variable denticity ligand comprising one or two nitrogen donor atom or atoms independently substituted by an aromatic or heteroaromatic ring, wherein the ortho positions of said ring(s) are substituted by groups other than H or alkyl; provided that at least one of the ortho positions of at least one of said aromatic or heteroaromatic rings is substituted by an aryl or heteroaryl group.
In a twenty-eighth aspect, the ortho positions of the aromatic or heteroaromatic ring(s) of the twenty-fourth, twenty-fifth, twenty-sixth, or twenty-seventh aspect are substituted by aryl or heteroaryl groups.
In a first preferred embodiment of the twenty-fourth, twenty-fifth, twenty-sixth, twenty-seventh or twenty-eighth aspect, the half-life for thermal decomposition is greater than 10 min in solution at 60xc2x0 C., 200 psig ethylene, and the average apparent catalyst activity of said catalyst is greater than 100,000 mol C2H4/mol catalyst/h. In a second, more preferred embodiment of these aspects, the half-life for thermal decomposition is greater than 20 minutes, and the average apparent catalyst activity of said catalyst is greater than 1,000,000 mol C2H4/mol catalyst/h. In a third, also more preferred embodiment of these aspects, the half-life for thermal decomposition of said catalyst is greater than 30 min. In a fourth, especially preferred embodiment of the first, second, and third embodiments of these aspects, the Group 8-10 metal is Ni. In a fifth preferred embodiment of these aspects, the process temperature is between about 60 and about 150xc2x0 C., more preferably between about 100 and about 150xc2x0 C. In a sixth, more preferred embodiment of these aspects, the bidentate or variable denticity ligand is selected from Set 12: 
wherein:
R6a and R6b are each independently an aromatic or heteroaromatic ring wherein the ortho positions of said ring(s) are substituted by groups other than H or alkyl; provided that at least one of the ortho positions of at least one of said aromatic or heteroaromatic rings is substituted by an aryl or heteroaryl group;
and R2x and R2y are each independently H, hydrocarbyl, substituted hydrocarbyl, heteroatom connected hydrocarbyl, or heteroatom connected substituted hydrocarbyl, and may be linked by a bridging group.
In a seventh, especially preferred embodiment of the twenty-fourth, twenty-fifth, twenty-sixth, twenty-seventh or twenty-eighth aspect, the Group 8-10 transition metal is nickel and the bidentate or variable denticity ligand is selected from Set 13: 
wherein:
R7a-d are groups other than H or alkyl; provided that at least one of R7a-d is an aryl or heteroaryl group;
R2x and R2y are each independently H, hydrocarbyl, substituted hydrocarbyl, heteroatom connected hydrocarbyl, or heteroatom connected substituted hydrocarbyl, and may be linked by a bridging group; and
R3a-f are each independently H, hydrocarbyl, substituted hydrocarbyl, heteroatom connected hydrocarbyl, heteroatom connected substituted hydrocarbyl, fluoroalkyl, silyl, boryl, fluoro, chloro, bromo, cyano, or nitro; in addition, any two of R3a-f may be linked by a bridging group.
In an eighth, also especially preferred embodiment of the twenty-fourth, twenty-fifth, twenty-sixth, twenty-seventh or twenty-eighth aspect, the composition is attached to a solid support, with silica being an especially preferred solid support and reaction temperatures between about 60 and about 100xc2x0 C. also being especially preferred in this embodiment.
In the case of gas phase olefin polymerization reactions, it can sometimes be advantageous if the catalyst can be introduced into the olefin polymerization reactor in an inactive form, and subsequently activated. When the catalyst is introduced in a fully activated form, there are sometimes problems with overheating of the supported catalyst particle, which initially has a very high rate of heat generation per unit volume. Overheating can result in catalyst deactivation, or excessive agglomeration of the polymer particles, or both. In addition, unfavorable static charge behavior may be observed, causing the freshly introduced particles to migrate to the reactor walls and give rise to deleterious sheeting phenomena. It is therefore another object of the current invention to describe methods of activating the catalyst in the gas phase olefin polymerization reactor itself.
Thus, in a twenty-ninth aspect, this invention also relates to a process for olefin polymerization comprising: contacting one or more olefin monomers with a single site catalyst attached to a solid support, wherein said catalyst comprises a cationic Group 4-11 transition metal complex and a weakly coordinating counteranion, and wherein said catalyst is introduced into a gas phase olefin polymerization reactor in an inactive form which is subsequently activated by reaction with a second compound Y1 to form said catalyst in said reactor.
Preferred Group 4-11 transition metals in this twenty-ninth aspect include Ti, Zr, Hf, Ni, Co, and Fe. Preferred second compounds Y1 in this aspect include trialkylaluminum or dialkylzinc compounds, with trimethylaluminum being especially preferred. In a more preferred embodiment, said inactive form of said catalyst is selected from Set 14, said weakly coordinating counteranion is either formed by reaction of said inactive form of said catalyst with Y1, or is selected from the group consisting of B(C6F5)4xe2x88x92, B(3,5-bis(trifluoromethyl)phenyl)4xe2x88x92[(C6F5)3B-(imidazole)-B(C6F5)3]xe2x88x92, BF4xe2x88x92, and [(C6F5)3B-CN-B(C6F5)3]xe2x88x92, and Y1 is trimethylaluminum; 
wherein:
R2a,b,x,y are each independently H, hydrocarbyl, substituted hydrocarbyl, heteroatom connected hydrocarbyl, heteroatom connected substituted hydrocarbyl, silyl, boryl, or ferrocenyl; in addition, any two of R2a,b,x,y may be linked by a bridging group;
R3a-m are each independently H, hydrocarbyl, substituted hydrocarbyl, heteroatom connected hydrocarbyl, heteroatom connected substituted hydrocarbyl, fluoroalkyl, silyl, boryl, fluoro, chloro, bromo, cyano, or nitro; in addition, any two of R3a-m may be linked by a bridging group;
A1 is halide or a monoanionic group which is capable of reacting with Y1 to generate an active olefin polymerization catalyst, provided that in the absence of Y1, A1 is such that said inactive form of said single site catalyst is at least 10 times less active as a catalyst for olefin polymerization than said active olefin polymerization catalyst;
A2 and A3 are each independently hydrocarbyl, halide, O(hydrocarbyl) or O(substituted hydrocarbyl), provided that at least one of A2 and A3 is capable of being abstracted by Y1 to form a weakly coordinating counteranion, and the other is either capable of inserting an olefin to initiate polymer chain growth, or is capable of being exchanged with a group on Y1 which can then initiate chain growth;
G and G4 are divalent bridging hydrocarbyl, substituted hydrocarbyl, silyl, heteroatom connected hydrocarbyl, or heteroatom connected substituted hydrocarbyl; and
Xxe2x88x92 is a weakly coordinating anion.
In a thirtieth aspect, this invention also relates to a process wherein the catalyst of the twenty-fourth, twenty-fifth, twenty-sixth, twenty-seventh or twenty-eighth aspect is introduced into a gas phase olefin polymerization reactor in an inactive form attached to a solid support, and wherein said catalyst is subsequently activated by a second compound Y1 in said reactor. In a first preferred embodiment of this thirtieth aspect, the bidentate or variable denticity ligand is selected from Set 15: 
wherein:
R6a and R6b are each independently an aromatic or heteroaromatic ring wherein the ortho positions of said ring(s) are substituted by groups other than H or alkyl; provided that at least one of the ortho positions of at least one of said aromatic or heteroaromatic rings is substituted by an aryl or heteroaryl group;
and R2x and R2y are each independently H, hydrocarbyl, substituted hydrocarbyl, heteroatom connected hydrocarbyl, or heteroatom connected substituted hydrocarbyl, and may be linked by a bridging group.
In a second, more preferred embodiment of the thirtieth aspect, (i) the Group 8-10 transition metal is nickel, (ii) the weakly coordinating counteranion is either formed by reaction of said inactive form of said catalyst with a volatile second compound Y1, or is selected from the group consisting of B(C6F5)4xe2x88x92, B(3,5-bis(trifluoromethyl)phenyl)4xe2x88x92, [(C6F5)3B-(imidazole)-B(C6F5)3]xe2x88x92, BF4xe2x88x92, and [(C6F5)3Bxe2x80x94CNxe2x80x94B(C6F5)3]xe2x88x92, (iii) Y1 is trimethylaluminum, and (iv) the bidentate or variable denticity ligand is selected from Set 16; 
wherein:
R7a-d are groups other than H or alkyl; provided that at least one of R7a-d is an aryl or heteroaryl group;
R2x and R2y are each independently H, hydrocarbyl, substituted hydrocarbyl, heteroatom connected hydrocarbyl, or heteroatom connected substituted hydrocarbyl, and may be linked by a bridging group; and
R3a-f are each independently H, hydrocarbyl, substituted hydrocarbyl, heteroatom connected hydrocarbyl, heteroatom connected substituted hydrocarbyl, fluoroalkyl, silyl, boryl, fluoro, chloro, bromo, cyano, or nitro; in addition, any two of R3a-f may be linked by a bridging group.
In a thirty-first aspect, this invention also relates to a process wherein said aromatic or heteroaromatic rings of the catalyst of the twenty-fourth, twenty-fifth, twenty-sixth, twenty-seventh or twenty-eighth aspect is selected from Set 17; 
wherein:
R7a,b are groups other than H or alkyl; provided that at least one of R7a,b is an aryl or heteroaryl group;
R3a-k are each independently H, hydrocarbyl, substituted hydrocarbyl, heteroatom connected hydrocarbyl, heteroatom connected substituted hydrocarbyl, fluoroalkyl, silyl, boryl, fluoro, chloro, bromo, cyano, or nitro; in addition, any two of R3a-k may be linked by a bridging group; and
E5 is O, S, Se, or NR3b.
In this disclosure, symbols ordinarily used to denote elements in the Periodic Table and commonly abbreviated groups, take their ordinary meaning, unless otherwise specified. Thus, N, O, S, P, and Si stand for nitrogen, oxygen, sulfur, phosphorus, and silicon, respectively, while Me, Et, Pr, iPr, Bu, tBu and Ph stand for methyl, ethyl, propyl, iso-propyl, butyl, tert-butyl and phenyl, respectively.
A xe2x80x9c1-pyrrolyl or substituted 1-pyrrolylxe2x80x9d group refers to a group of formula II below: 
wherein R3a-d are each independently H, hydrocarbyl, substituted hydrocarbyl, heteroatom connected hydrocarbyl, heteroatom connected substituted hydrocarbyl, fluoroalkyl, silyl, boryl, fluoro, chloro, bromo, cyano, or nitro; in addition, any two or more of R3a-d may be linked by a bridging group or groupsto form bicyclic or polycyclic ring systems including carbazol-9-yl and indol-1-yl.
A xe2x80x9chydrocarbylxe2x80x9d group means a monovalent or divalent, linear, branched or cyclic group which contains only carbon and hydrogen atoms. Examples of monovalent hydrocarbyls include the following: C1-C20 alkyl; C1-C20 alkyl substituted with one or more groups selected from C1-C20 alkyl, C3-C8 cycloalkyl, and aryl; C3-C8 cycloalkyl; C3-C8 cycloalkyl substituted with one or more groups selected from C1-C20 alkyl, C3-C8 cycloalkyl, and aryl; C6-C14 aryl; and C6-C14 aryl substituted with one or more groups selected from C1-C20 alkyl, C3-C8 cycloalkyl, and aryl. Examples of divalent (bridging) hydrocarbyls include: xe2x80x94CH2xe2x80x94, xe2x80x94CH2CH2xe2x80x94, xe2x80x94CH2CH2CH2xe2x80x94, and 1,2-phenylene.
The term xe2x80x9carylxe2x80x9d refers to an aromatic carbocyclic monoradical, which may be substituted or unsubstituted, wherein the substituents are halo, hydrocarbyl, substituted hydrocarbyl, heteroatom attached hydrocarbyl, heteroatom attached substituted hydrocarbyl, nitro, cyano, fluoroalkyl, sulfonyl, and the like. Examples include: phenyl, naphthyl, anthracenyl, phenanthracenyl, 2,6-diphenylphenyl, 3,5-dimethylphenyl, 4-nitrophenyl, 3-nitrophenyl, 4-methoxyphenyl, 4-dimethylaminophenyl, and the like.
A xe2x80x9cheterocyclic ringxe2x80x9d refers to a carbocyclic ring wherein one or more of the carbon atoms has been replaced by an atom selected from the group consisting of O, N, S, P, Se, As, Si, B, and the like.
A xe2x80x9cheteroaromatic ringxe2x80x9d refers to an aromatic heterocycle; examples include pyrrole, furan, thiophene, indene, imidazole, oxazole, isoxazole, carbazole, thiazole, pyrimidine, pyridine, pyridazine, pyrazine, benzothiophene, and the like.
A xe2x80x9cheteroarylxe2x80x9d refers to a heterocyclic monoradical which is aromatic; examples include 1-pyrrolyl, 2-pyrrolyl, 3-pyrrolyl, furyl, thienyl, indenyl, imidazolyl, oxazolyl, isoxazolyl, carbazolyl, thiazolyl, pyrimidinyl, pyridyl, pyridazinyl, pyrazinyl, benzothienyl, and the like, and substituted derivatives thereof.
A xe2x80x9csilylxe2x80x9d group refers to a SiR3 group wherein Si is silicon and R is hydrocarbyl or substituted hydrocarbyl or silyl, as in Si(SiR3)3.
A xe2x80x9cborylxe2x80x9d group refers to a BR2 or B(OR)2 group, wherein R is hydrocarbyl or substituted hydrocarbyl.
A xe2x80x9cheteroatomxe2x80x9d refers to an atom other than carbon or hydrogen. Preferred heteroatoms include oxygen, nitrogen, phosphorus, sulfur, selenium, arsenic, chlorine, bromine, silicon, and fluorine.
A xe2x80x9csubstituted hydrocarbylxe2x80x9d refers to a monovalent, divalent, or trivalent hydrocarbyl substituted with one or more heteroatoms. Examples of monovalent substituted hydrocarbyls include: 2,6-dimethyl-4-methoxyphenyl, 2,6-diisopropyl-4-methoxyphenyl, 4-cyano-2,6-dimethylphenyl, 2,6-dimethyl-4-nitrophenyl, 2,6-difluorophenyl, 2,6-dibromophenyl, 2,6-dichlorophenyl, 4-methoxycarbonyl-2,6-dimethylphenyl, 2-tert-butyl-6-chlorophenyl, 2,6-dimethyl-4-phenylsulfonylphenyl, 2,6-dimethyl-4-trifluoromethylphenyl, 2,6-dimethyl-4-trimethylammoniumphenyl (associated with a weakly coordinated anion), 2,6-dimethyl-4-hydroxyphenyl, 9-hydroxyanthr-10-yl, 2-chloronapth-1-yl, 4-methoxyphenyl, 4-nitrophenyl, 9-nitroanthr-10-yl, -CH2OCH3, cyano, trifluoromethyl, and fluoroalkyl. Examples of divalent (bridging) substituted hydrocarbyls include: 4-methoxy-1,2-phenylene, 1-methoxymethyl-1,2-ethanediyl, 1,2-bis(benzyloxymethyl)-1,2-ethanediyl, and 1-(4-methoxyphenyl)-1,2-ethanediyl.
A xe2x80x9cheteroatom connected hydrocarbylxe2x80x9d refers to a group of the type E10(hydrocarbyl), E20H(hydrocarbyl), or E20(hydrocarbyl)2, where E10 is an atom selected from Group 16 and E20 is an atom selected from Group 15.
A xe2x80x9cheteroatom connected substituted hydrocarbylxe2x80x9d refers to a group of the type E10(substituted hydrocarbyl), E20H(substituted hydrocarbyl), or E20(substituted hydrocarbyl)2, where E10 is an atom selected from Group 16 and E20 is an atom selected from Group 15.
The term xe2x80x9cfluoroalkylxe2x80x9d as used herein refers to a C1-C20 alkyl group substituted by one or more fluorine atoms.
An xe2x80x9colefinxe2x80x9d refers to a compound of the formula R1aCHxe2x95x90CHR1b, where R1a and R1b may independently be H, hydrocarbyl, substituted hydrocarbyl, fluoroalkyl, silyl, O(hydrocarbyl), or O(substituted hydrocarbyl), and where R1a and R1b may be connected to form a cyclic olefin, provided that in all cases, the substituents R1a and R1b are compatible with the catalyst. In the case of most Group 4-7 catalysts, this will generally mean that the olefin should not contain good Lewis base donors, since this will tend to severely inhibit catalysis. Preferred olefins for such catalysts include ethylene, propylene, butene, hexene, octene, cyclopentene, norbornene, and styrene.
In the case of the Group 8-10 catalysts, Lewis basic substituents on the olefin will tend to reduce the rate of catalysis in most cases; however, useful rates of homopolymerization or copolymerization can nonetheless be achieved with some of those olefins. Preferred olefins for such catalysts include ethylene, propylene, butene, hexene, octene, and fluoroalkyl substituted olefins, but may also include, in the case of palladium and some of the more functional group tolerant nickel catalysts, norbornene, substituted norbornenes (e.g., norbornenes substituted at the 5-position with halide, siloxy, silane, halo carbon, ester, acetyl, alcohol, or amino groups), cyclopentene, ethyl undecenoate, acrylates, vinyl ethylene carbonate, 4-vinyl-2,2-dimethyl- 1,3-dioxolane, and vinyl acetate.
In some cases, the Group 8-10 catalysts can be inhibited by olefins which contain additional olefinic or acetylenic functionality. This is especially likely if the catalyst is prone to xe2x80x9cchain-runningxe2x80x9d wherein the catalyst can migrate up and down the polymer chain between insertions, since this can lead to the formation of relatively unreactive xcfx80-allylic intermediates when the olefin monomer contains additional unsaturation. Such effects are best determined on a case-by-case basis, but may be predicted to some extent through knowledge of how much branching is observed with a given catalyst in ethylene homopolymerizations; those catalysts which tend to give relatively high levels of branching with ethylene will tend to exhibit lower rates when short chain diene co-monomers are used under the same conditions. Longer chain dienes tend to be less inhibitory than shorter chain dienes, when other factors are kept constant, since the catalyst has farther to migrate to form the xcfx80-allyl, and another insertion may intervene first.
Similar considerations apply to unsaturated esters which are capable of inserting and chain-running to form relatively stable intramolecular chelate structures wherein the Lewis basic ester functionality occupies a coordination site on the catalyst. In such cases, short chain unsaturated esters, such as methyl acrylate, tend to be more inhibitory than long chain esters, such as ethyl undecenoate, if all other factors are kept constant.
The term xe2x80x9cxcex1-olefinxe2x80x9d as used herein is a 1-alkene with from 3 to 40 carbon atoms.
A xe2x80x9cxcfx80-allylxe2x80x9d group refers to a monoanionic group with three sp2 carbon atoms bound to a metal center in a xcex73-fashion. Any of the three sp2 carbon atoms may be substituted with a hydrocarbyl, substituted hydrocarbyl, heteroatom connected hydrocarbyl, heteroatom connected substituted hydrocarbyl, or O-silyl group.
Examples of xcfx80-allyl groups include: 
The term xcfx80-benzyl group denotes an xcfx80-allyl group where two of the sp2 carbon atoms are part of an aromatic ring. Examples of xcfx80-benzyl groups include: 
A xe2x80x9cbridging groupxe2x80x9d refers to an atom or group which links two or more groups, which has an appropriate valency to satisfy its requirements as a bridging group, and which is compatible with the desired catalysis. Suitable examples include divalent or trivalent hydrocarbyl, substituted hydrocarbyl, heteroatom connected hydrocarbyl, heteroatom connected substituted hydrocarbyl, substituted silicon(IV), boron(III), N(III), P(III), and P(V), xe2x80x94C(O)xe2x80x94, xe2x80x94SO2xe2x80x94, xe2x80x94C(S)xe2x80x94, xe2x80x94B(OMe)xe2x80x94, xe2x80x94C(O)C(O)xe2x80x94, O, S, and Se. In some cases, the groups which are said to be xe2x80x9clinked by a bridging groupxe2x80x9d are directly bonded to one another, in which case the term xe2x80x9cbridging groupxe2x80x9d is meant to refer to that bond. By xe2x80x9ccompatible with the desired catalysis,xe2x80x9d we mean the bridging group either does not interfere with the desired catalysis, or acts to usefully modify the catalyst activity or selectivity.
The term xe2x80x9cweakly coordinating anionxe2x80x9d is well known in the art per se and generally refers to a large bulky anion capable of delocalization of the negative charge of the anion. The importance of such delocalization depends to some extent on the nature of the transition metal comprising the cationic active species, with the Group 4-6 transition metals requiring less coordinating anions, such as B(C6F5)4xe2x88x92, than many Group 8-10 transition metal based catalysts, which can in some cases give active catalysts with BF4xe2x88x92 counteranions. Weakly coordinating anions, not all of which would be considered bulky, include, but are not limited to: B(C6F5)4xe2x88x92, PF6xe2x88x92, BF4xe2x88x92, SbF6xe2x88x92, (Ph)4Bxe2x88x92 wherein Ph=phenyl, and Ar4Bxe2x88x92 wherein Ar4Bxe2x88x92=tetrakis[3,5-bis(trifluoromethyl)phenyl]-borate. The weakly coordinating nature of such anions is known and described in the literature (S. Strauss et al., Chem. Rev., 1993, 93, 927).
The term xe2x80x9cagosticxe2x80x9d is known to those skilled in the art, and is generally used to refer to a weak bonding interaction between a Cxe2x80x94H bond and a coordinatively unsaturated transition metal. It is used herein to denote a weak bonding interaction between any or all of the atoms of the ortho-aryl or ortho-heteroaryl groups of the ligands described in the twenty-fourth and higher aspects of the present invention, and a coordinatively unsaturated Group 8-10 transition metal center to which said ligands are complexed. By xe2x80x9cweak bonding interactionxe2x80x9d we mean a bond that is sufficiently weak that it is formed reversibly under olefin polymerization reaction conditions, so that it does not, for example, preclude the binding and insertion of olefin monomer.
The term xe2x80x9corthoxe2x80x9d is used herein in the context of the ligands of the twenty-fourth and higher aspects to denote the positions which are adjacent to the point of attachment of said aromatic or heteroaromatic ring to the ligated nitrogen(s). In the case of a 1-attached, 6-membered ring, we mean the 2- and 6-positions. In the case of a 1-attached, 5-membered ring, we mean the 2- and 5-positions. In the case of 1-attached, fused ring aromatic or heteroaromatic rings, we mean the first positions which can be substituted; for example, in the case of 1-naphthyl, these would be the 2- and 8-positions; in the case of 9-anthracenyl, these would be the 1- and 8-positions.
The term xe2x80x9cvariable denticityxe2x80x9d is used herein in the context of otherwise bidentate ligands to refer to the reversible formation of a third binding interaction between the ligand and the Group 8-10 transition metal center to which it is complexed.
The abbreviation xe2x80x9cacacxe2x80x9d refers to acetylacetonate. In general, substituted acetylacetonates, wherein one or more hydrogens in the parent structure have been replaced by a hydrocarbyl, substituted hydrocarbyl, or fluoroalkyl, may be used in place of the xe2x80x9cacacxe2x80x9d. Hydrocarbyl substituted acetylacetonates may be preferred in some cases when it is important, for example, to improve the solubility of a (ligand)Ni(acac)BF4 salt in mineral spirits.
The term xe2x80x9chalf-life for thermal decompositionxe2x80x9d refers to the time required for the catalyst to lose half of its activity, as determined under substantially non-mass transport limited conditions.
The phrase xe2x80x9csubstantially non-mass transport limited conditionsxe2x80x9d refers to the fact that when an ethylene polymerization reaction is conducted in solution using gaseous ethylene as the monomer or co-monomer, the rate of dissolution of ethylene in the liquid phase can often be the turnover-limiting step of the catalytic cycle, so that the apparent catalyst activity is less than would be observed under improved mass transport conditions. Mass transport limitations may typically be reduced by either increasing the partial pressure of ethylene, improving the agitation and mixing of the gaseous phase with the liquid phase, or decreasing the catalyst loading, to the point where the polymerization reaction rate exhibits a first order dependence on the amount of catalyst charged to the reactor, and the reaction can then be considered to be substantially non-mass transport limited.
The phrase xe2x80x9capparent catalyst activityxe2x80x9d refers to the moles of monomer consumed per mole of catalyst per unit time, without consideration of the impact of mass transport limitations.
The phrase xe2x80x9cwherein said catalyst composition exhibits improved thermal stabilityxe2x80x9d refers to a catalyst composition which has a half-life for thermal decomposition which is at least 2 times, preferably 5 times, and most preferably 10 times longer than that observed under substantially non-mass transport limited conditions for an otherwise structurally identical catalyst composition lacking the novel ortho-aryl substitution pattern of the catalysts of the current invention, described in the twenty-fourth, twenty-fifth, twenty-sixth, twenty-seventh and twenty-eighth aspects of the current invention.
The phrase xe2x80x9can amount of hydrogen effective to achieve chain transferxe2x80x9d refers to the ability of hydrogen to react with an olefin polymerization catalyst to cleave off a growing polymer chain and initiate a new chain. In most cases, this is believed to involve hydrogenolysis of the metal-carbon bond of the growing polymer chain, to form a metal hydride catalytic intermediate, which can then react with the olefin monomer to initiate a new chain. In the context of the current invention, an effective amount is considered to be that amount of hydrogen which reduces both the number average molecular weight and the weight average molecular weight of the polymer by at least 10%, relative to an otherwise similar reaction conducted in the absence of hydrogen. In this context, xe2x80x9cotherwise similarxe2x80x9d denotes that the catalyst, catalyst loading, solvent, solvent volume, agitation, ethylene pressure, co-monomer concentration, reaction time, and other process relevant parameters are sufficiently similar that a valid comparison can be made.
In general, previously reported catalysts lacking the novel ortho-aryl substitution pattern of the current invention are far less productive in the presence of an amount of hydrogen effective to achieve chain transfer than they are under otherwise similar conditions without hydrogen. In order to quantify this effect, the following terms are defined.
The productivity P is defined as the grams of polymer produced per mole of catalyst; over a given period of time. The productivity Phydrogen is define as the grams of polymer produced per mole of catalyst in the presence of an amount of hydrogen effective to achieve chain transfer, in an otherwise similar reaction conducted for the same period of time. Catalysts lacking the novel ortho-aryl substitution pattern of the catalyst compositions of the current invention typically exhibit ratios PhydrogenP less than or equal to 0.05 under substantially non-mass transport limited conditions.
The phrase xe2x80x9cimproved stability in the presence of an amount of hydrogen effective to achieve chain transferxe2x80x9d means that the ratio Phydrogen/P is at least 0.1 under substantially non-mass transport limited conditions. Preferred catalysts of the present invention exhibit a ratio Phydrogen/P greater than or equal to 0.2 under substantially non-mass transport limited conditions. Especially preferred catalysts of the present invention exhibit a ratio Phydrogen/P greater than or equal to 0.5 under substantially non-mass transport limited conditions.
The phrase xe2x80x9cone or more olefinsxe2x80x9d refers to the use of one or more chemically different olefin monomer feedstocks, for example, ethylene and propylene.
The term xe2x80x9csingle site catalystxe2x80x9d is used as commonly defined, and preferably refers to an olefin polymerization catalyst which can be dissolved and activated to form a single active species, capable of reacting with one or more olefin monomers to form a polymer having a narrow molecular weight distribution, typically characterized by a Mw/Mn less than 4. Many examples of such catalysts are illustrated herein; additional specific examples are given in the following references: EP 420,436 (1991); EP 416,815 (1991); Science, 1995, 267, 217; EP 874,005 (1998); J. Am. Chem. Soc., 1996, 118, 10008; J. Am. Chem. Soc., 1997, 119, 3830, J. Am. Chem. Soc., 1999, 121, 5797; WO 94/14854, EP 0 532 098 A1; EP 0 641 804 A2, EP 0 816 384 A2; WO 94/11410; WO 94/0147; WO 96/23010, U.S. Pat. No. 5,866,663, U.S. Pat. Nos. 5,886,224, 5,891,963, 5,880,323, 5,880,241, J. Am. Chem. Soc., 1995, 117, 6414; WO 97/02298; WO 98/40374, WO 98/37110, WO 98/47933, WO 98/40420; WO 97/17380, WO 97/48777, WO 97/48739, WO 97/48740; WO 99/02472; WO 98/27124; WO 99/12981; WO 98/30610, WO 98/30609, WO 98/42665, WO 98/42664; U.S. Pat. Nos. 4,564,647,; 4,752,597; 5,106,804; 5,132,380; 5,227,440; 5,296,565; 5,324,800; 5,331,071; 5,332,706; 5,350,723; 5,399,635; 5,466,766; 5,468,702; 5,474,962; 5,578,537 and 5,863,853. The entire contents of these patents are incorporated herein by reference.
The term xe2x80x9cinactive formxe2x80x9d is used to refer to a transition metal complex which serves as a precursor to the active olefin polymerization catalyst, and has either no polymerization activity prior to activation by the second compound Y1, or is at least 10 times less active than the product of activation.
Compound Y1 is a compound which is capable of reacting with said inactive form of said catalyst to generate an active olefin polymerization catalyst composition, and which also has a volatility effective to activate said inactive form of said catalyst under the conditions of a gas phase olefin polymerization reactor. Examples include trimethylaluminum, dimethylzinc, MenEt3-nAl (n=0-3), diethylzinc, and Et2AlCl.
The phrase xe2x80x9ccapable of inserting an olefinxe2x80x9d refers to a group Z bonded to the transition metal M, which can insert an olefin monomer of the type R1aCHxe2x95x90CHR1b to form a moiety of the type Mxe2x80x94CHR1axe2x80x94CHR1bxe2x80x94Z, which can subsequently undergo further olefin insertion to form a polymer chain; wherein R1a and R1b may independently be H, hydrocarbyl, substituted hydrocarbyl, fluoroalkyl, silyl, O(hydrocarbyl), or O(substituted hydrocarbyl), and wherein R1a and R1b may be connected to form a cyclic olefin, provided that in all cases, the substituents R1a and R1b are compatible with the desired catalysis; wherein additional groups will be bound to the transition metal M to comprise the actual catalyst, as discussed in more detail below.
The phrase xe2x80x9ccapable of being exchanged with a group on said volatile second compound Y1xe2x80x9d refers to the ability of some activators to transfer a group which will be capable of inserting an olefin to the transition metal, in exchange for a group which is not capable of inserting an olefin.
The term xe2x80x9cborataarylxe2x80x9d is used to refer to a monoanionic heterocyclic group of formula XXX: 
wherein:
R3a-e are each independently H, hydrocarbyl, substituted hydrocarbyl, heteroatom connected hydrocarbyl, hetero atom connected substituted hydrocarbyl, fluoroalkyl, silyl, boryl, fluoro, chloro, bromo, cyano, or nitro; in addition, any two of R3a-e may be linked by a bridging group;
R4a is hydrocarbyl, substituted hydrocarbyl, heteroatom connected hydrocarbyl, or heteroatom connected substituted hydrocarbyl; and wherein
any one of R3a-e or R4a may function as a divalent bridging group to connect the borataaryl to the remainder of the ligand.
In general, the catalysts of the present invention can be made sufficiently sterically hindered that chain transfer is slow with respect to chain propagation so that a chain of degree of polymerization (DP) of 10 or more results. For example, in the case of a catalyst system comprising a catalyst of the type [(ligand)Fe(T1a)(L)]+Xxe2x88x92, where T1a is a hydrogen atom, hydrocarbyl, or other group capable of inserting an olefin, L is an olefin or neutral donor group capable of being displaced by an olefin, Xxe2x88x92 is a weakly coordinating anion, and ligand is a compound of formula h17, the catalyst system reacts with ethylene to form low molecular weight polymer. However, it is to be understood that less hindered forms of these catalysts, for example those derived from h19, generally comprising ligands which do not contain bulky substituents, can also be used as dimerization or oligomerization catalysts.
The degree of steric hindrance at the active catalyst site required to give slow chain transfer, and thus form polymer, depends on a number of factors and is often best determined by experimentation. These factors include: the exact structure of the catalyst, the monomer or monomers being polymerized, whether the catalyst is in solution or attached to a solid support, and the temperature and pressure. Polymer is defined herein as corresponding to a degree of polymerization, DP, of about 10 or more; oligomer is defined as corresponding to a DP of 2 to about 10.
A variety of protocols may be used to generate active polymerization catalysts comprising transition metal complexes of various nitrogen, phosphorous, oxygen and sulfur donor ligands. Examples include (i) the reaction of a Group 4 metallocene dichloride with MAO, (ii) the reaction of a Group 4 metallocene dimethyl complex with N,N-diethylanilinium tetrakis(pentafluorophenyl)borate, (iii) the reaction of a Group 8 or 9 metal dihalide complex of a tridentate N-donor ligand with an alkylaluminum reagent, (iv) the reaction of a Group 8 or 9 metal dialkyl complex of a tridentate N-donor ligand with MAO or HB(3,5-bis(trifluoromethyl)phenyl)4, (v) the reaction of (Me2N)4Zr with 2 equivalents of an N-pyrrol-1-ylsalicylimine, followed by treatment of the product of that reaction with Me3SiCl and then a triisobutylaluminum-modified methylaluminoxane, and (vi) the reaction of a nickel or palladium dihalide complex of a bidentate N-donor ligand with an alkylaluminum reagent. Additional methods described herein include the reaction of (tridentate N-donor ligand)M(acac)B(C6F5)4 salts with an alkylaluminum reagent, where M is Fe(II) or Co(II), and the reaction of (bidentate N-donor ligand)Ni(acac)X salts with an alkylaluminum reagent, where X is a weakly coordinating anion, such as B(C6F5)4xe2x88x92, BF4xe2x88x92, PF6xe2x88x92, SbF6xe2x88x92 and OS(O)2CF3xe2x88x92. Cationic [(ligand)M(xcfx80-allyl)]+ complexes with weakly coordinating counteranions, where M is a Group 10 transition metal, are often also suitable catalyst precursors, requiring only exposure to olefin monomer and in some cases elevated temperatures (40-100 xc2x0 C.) or added Lewis acid, or both, to form an active polymerization catalyst.
More generally, a variety of (ligand)nM(Z1a)(Z1b) complexes, where xe2x80x9cligandxe2x80x9d refers to a compound of the present invention, and comprises at least one nitrogen donor wherein the nitrogen ligated to the metal M is substituted by a 1-pyrrolyl or substituted 1-pyrrolyl group, n is 1 or 2, M is a Group 4-10 transition metal, and Z1a and Z1b are univalent groups, or may be taken together to form a divalent group, may be reacted with one or more compounds, collectively referred to as compound Y2, which function as co-catalysts or activators, to generate an active catalyst of the form [(ligand)nM(T1a)(L)]+Xxe2x88x92, where n is 1 or 2, T1a is a hydrogen atom or hydrocarbyl, L is an olefin or neutral donor group capable of being displaced by an olefin, M is a Group 4-10 transition metal, and Xxe2x88x92 is a weakly coordinating anion. When Z1a and Z1b are both halide, examples of suitable compound Y2 include: methylaluminoxane (hereinafter MAO) and other aluminum sesquioxides, R3Al, R2AlCl, and RAlCl2 (wherein R is alkyl, and plural groups R may be the same or different). When Z1a and Z1b are both alkyl, examples of suitable compound Y2 include: MAO and other aluminum sesquioxides, R3Al, R2AlCl, RAlCl2 (wherein R is alkyl, and plural groups R may be the same or different), B(C6F5)3, R03Sn[BF4] (wherein R0 is hydrocarbyl or substituted hydrocarbyl and plural groups R0 may be the same or different), H+Xxe2x88x92, wherein Xxe2x88x92 is a weakly coordinating anion, for example, tetrakis[3,5-bis(trifluoromethyl)phenyl]borate, and Lewis acidic or Bronsted acidic metal oxides, for example, montmorillonite clay. In some cases, for example, when Z1a and Z1b are both halide or carboxylate, sequential treatment with a metal hydrocarbyl, followed by reaction with a Lewis acid, may be required to generate an active catalyst. Suitable examples of metal hydrocarbyls include: MAO, other aluminum sesquioxides, R3Al, R2AlCl, RAlCl2 (wherein R is alkyl, and plural groups R may be the same or different), Grignard reagents, organolithium reagents, and diorganozinc reagents. Examples of suitable Lewis acids include: MAO, other aluminum sesquioxides, R3Al, R2AlCl, RAlCl2 (wherein R is alkyl, and plural groups R may be the same or different), B(C6F5)3, R03Sn[BF4] (wherein R0 is hydrocarbyl or substituted hydrocarbyl and plural groups R0 may be the same or different), and Lewis acidic metal oxides.
The term xe2x80x9calkylaluminumxe2x80x9d is used to refer to compounds containing at least one alkyl group bonded to Al (III), which are capable of reacting with a metal complex of the present invention to generate an active olefin polymerization catalyst. In general, this will involve exchanging one or more alkyl groups from the aluminum with a monoanionic atom or group on the metal complex pro-catalyst. In some cases, a hydride may be directly transferred from the xcex2-carbon of the aluminum alkyl to said metal complex. Subsequent abstraction of a second monoanionic atom or group from the metal complex may also be required to generate a cationic active catalyst. When the pro-catalyst is already a cationic metal complex, the role of the alkylaluminum may simply be to exchange an alkyl or hydride from the aluminum with a monoanionic group, such as acetylacetonate, attached to the metal complex. In the case of a cationic xcfx80-allyl or xcfx80-benzyl pro-catalyst, the alkylaluminum reagent may, in some cases, simply act as a Lewis acid, to promote conversion of the xcfx80-allyl or xcfx80-benzyl to a "sgr"-allyl or "sgr"-benzyl bonding mode, thereby facilitating binding and insertion of the olefin monomer. When a cationic pro-catalyst is used with an alkylaluminum activator or co-catalyst, it should also be recognized that the starting counteranion (e.g. BF4xe2x88x92) may react with the alkylaluminum reagent to generate a new counteranion (or a mixture of several different counteranions) under olefin polymerization reaction conditions. Examples of alkylaluminum reagents include: MAO, other aluminum sesquioxides, Me3Al, EtAlCl2, Et2AlCl, R3Al, R2AlCl, RAlCl2 (wherein R is alkyl, and plural groups R may be the same or different), and the like.
The foregoing discussion is intended to illustrate that there are frequently many ways to generate an active catalyst, and that in some cases the structure of the active species has not been fully elucidated. It is, however, an object of this disclosure to teach that there are a variety of methods wherein the ligands of the present invention can be reacted with a suitable metal precursor, and optionally a co-catalyst, to generate an active olefin polymerization catalyst. Without wishing to be bound by theory, the inventors also believe that the active catalyst typically comprises the catalytically active metal, one or more ligands of the present invention, the growing polymer chain (or a hydride capable of initiating a new chain), and a site on the metal adjacent to the metal-alkyl bond of said chain where ethylene can coordinate, or at least closely approach, prior to insertion. Where specific structures for active catalysts have been implied herein, it should be understood that an object of this invention is to teach and claim that active catalysts comprising the ligands of the present invention are formed as the reaction products of the catalyst activation reactions disclosed herein, regardless of the detailed structures of those active species.
Active catalysts may, in some cases, be generated from more than one oxidation state of a given metal. For example, the present invention describes the use of both Co(III) and Co(II) catalyst precursors to effect olefin polymerization using MAO or other alkylaluminum co-catalysts. In some cases, the oxidation state of the active catalyst has not been unambiguously established, so that it is not known if the same metal can give rise to active catalysts with different oxidation states, or if different oxidation state precursors all give rise to the same oxidation state catalyst under polymerization conditions. The latter could arise, for example, by reduction of a Co(III) catalyst precursor to a Co(II) compound under reaction conditions. Where only one oxidation state of a given metal has been specified herein, it is therefore to be understood that other oxidation states of the same metal, complexed by the ligands of the present invention, can serve as catalyst precursors or active catalysts. When different oxidation state complexes of said ligands are used, appropriate changes in the ancillary ligands or the counteranion must obviously accompany any change in oxidation level to balance the charge. Examples where multiple oxidation state precurors are especially likely to be encountered include, but are not limited to, Ti(III)/Ti(IV), Fe(III)/Fe(II), and Co(III)/Co(II).
The catalysts of the present invention may be used in batch and continuous processes, in solution or slurry or gas phase processes.
In some cases, it is advantageous to attach the catalyst to a solid support. Examples of useful solid supports include: inorganic oxides, such as talcs, silicas, titania, silica/chromia, silica/chromia/titania, silica/alumina, zirconia, aluminum phosphate gels, silanized silica, silica hydrogels, silica xerogels, silica aerogels, montmorillonite clay and silica co-gels, as well as organic support materials such as polystyrene and functionalized polystyrene. (See, for example, S. B. Roscoe et al., xe2x80x9cPolyolefin Spheres from Metallocenes Supported on Non-Interacting Polystyrene,xe2x80x9d 1998, Science, 280, 270-273 (1998)).
Thus, in a preferred embodiment, the catalysts of the present invention are attached to a solid support (by xe2x80x9cattached to a solid supportxe2x80x9d is meant ion paired with a component on the surface, adsorbed to the surface or covalently attached to the surface) that has been pre-treated with a compound Y2. More generally, the compound Y2 and the solid support can be combined in any order and any number of compound(s) Y2 can be utilized. In addition, the supported catalyst thus formed may be treated with additional quantities of compound Y2. In another preferred embodiment, the compounds of the present invention are attached to silica that has been pre-treated with an alkylaluminum compound Y2, for example, MAO, Et3Al, iBu3Al, Et2AlCl, or Me3Al.
Such supported catalysts are prepared by contacting the transition metal compound, in a substantially inert solvent (by which is meant a solvent which is either unreactive under the conditions of catalyst preparation, or if reactive, acts to usefully modify the catalyst activity or selectivity) with MAO-treated silica for a sufficient period of time to generate the supported catalyst. Examples of substantially inert solvents include toluene, o-difluorobenzene, mineral spirits, hexane, CH2Cl2, and CHCl3.
In another preferred embodiment, the catalysts of the present invention are activated in solution under an inert atmosphere, and then adsorbed onto a silica support which has been pre-treated with a silylating agent to replace surface silanols by trialkylsilyl groups. Methods to pre-treat silicas in this way are known to those skilled in the art and may be achieved, for example, by heating the silica with hexamethyldisilazane and then removing the volatiles under vacuum. A variety of precurors and procedures may be used to generate the activated catalyst prior to said adsorption, including, for example, reaction of a (ligand)Ni(acac)B(C6F5)4 complex with Et2AlCl in a toluene/hexane mixture under nitrogen; where xe2x80x9cligandxe2x80x9d refers to a compound of the present invention.
In several cases, metal complexes are depicted herein with square planar, trigonal bipyramidal, or other coordination, however, it is to be understood that no specific geometry is implied.
The polymerizations may be conducted as solution polymerizations, as non-solvent slurry type polymerizations, as slurry polymerizations using one or more of the olefins or other solvent as the polymerization medium, or in the gas phase. One of ordinary skill in the art, with the present disclosure, would understand that the catalyst could be supported using a suitable catalyst support and methods known in the art. Substantially inert solvents, such as toluene, hydrocarbons, methylene chloride and the like, may be used. Propylene and 1-butene are excellent monomers for use in slurry-type copolymerizations and unused monomer can be flashed off and reused.
Temperature and olefin pressure have significant effects on polymer structure, composition, and molecular weight. Suitable polymerization temperatures are preferably from about 20xc2x0 C. to about 160xc2x0 C., more preferably 60xc2x0 C. to about 100xc2x0 C.
The catalysts of the present invention may be used alone, or in combination with one or more other Group 3-10 olefin polymerization or oligomerization catalysts, in solution, slurry, or gas phase processes. Such mixed catalysts systems are sometimes useful for the production of bimodal or multimodal molecular weight or compositional distributions, which may facilitate polymer processing or final product properties.
After the reaction has proceeded for a time sufficient to produce the desired polymers, the polymer can be recovered from the reaction mixture by routine methods of isolation and/or purification.
In general, the polymers of the present invention are useful as components of thermoset materials, as elastomers, as packaging materials, films, compatibilizing agents for polyesters and polyolefins, as a component of tackifying compositions, and as a component of adhesive materials.
High molecular weight resins are readily processed using conventional extrusion, injection molding, compression molding, and vacuum forming techniques well known in the art. Useful articles made from them include films, fibers, bottles and other containers, sheeting, molded objects and the like.
Low molecular weight resins are useful, for example, as synthetic waxes and they may be used in various wax coatings or in emulsion form. They are also particularly useful in blends with ethylene/vinyl acetate or ethylene/methyl acrylate-type copolymers in paper coating or in adhesive applications.
Although not required, typical additives used in olefin or vinyl polymers may be used in the new homopolymers and copolymers of this invention. Typical additives include pigments, colorants, titanium dioxide, carbon black, antioxidants, stabilizers, slip agents, flame retarding agents, and the like. These additives and their use in polymer systems are known per se in the art.
The ligands of the present invention may be prepared by methods known to those skilled in the art, wherein a substituted 1-aminopyrrole is condensed with a di-aldehyde or di-ketone to afford the desired ligands (Scheme II). The requisite substituted 1-aminopyrroles may be prepared by any of a variety of methods, including those shown in Scheme III. 
Other features of the invention will become apparent in the following description of working examples, which have been provided for illustration of the invention and are not intended to be limiting thereof.